Does the deceased feel those who visit him in the graveyard, and is it obligatory to stand before the grave, or is merely entering the graveyard sufficient?

There is no clear evidence that the deceased feels the presence of a visitor. However, the Sunnah (definition) is to visit graves, greet those within, and supplicate for them. Supplication benefits the deceased, and the visit offers reward for the visitor, serving as a reminder of death and the Hereafter. Standing at the cemetery's edge and offering greetings is sufficient, but drawing near the deceased's grave and supplicating for them is better and more complete.